Improvement in hot-air engines



1D. fir/217 UNITED STATES l.PnfrnNT OFFICE.

PHILANDER SHAW, OF BOSTON,'MASSACHUSETTS IMPROVEMENT IN HOT-Am ENGINi-:e

Specication forming part of Letters Patent No.` 33,799, dated November' 26, 1861.

To all what/11, it may conce77t-- Be, it known that I, PHILANDER SHAW, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in- Hot-Air or Calorie Engines; and I do hereby declare that the following, taken in connection with the drawings which accompany and form part of this specitication,is a description lof my invention so full and exact as to enable those skilled in the art to practice it.

The nature of my invention consists,'first,

l in an arrangement, substantiallysuch as herein is described and is also illustrated in the -'drawings, of two single-acting cylinders having their 'pistons coupled toa shaft having its cranks at right angles with each other, with a furnace and its' accessories centrally located,

or nearly so, between the said cylinders and within an air-tight casing, which forms a reservoir for compressed and heated'air and is so divided by partitions and diaphragms as to receive the cool supplyair at or near the exterior of thereserv'oir and to guide itinward by a tortuous passage to the furnace in substantiallysthe manner described, so that it shall absorb the heat radiated from such parts of the engine as receive the products of com- .fbustion, those parts of the engine-cylinders in which the pistons ll the bore being located outside of and upon the casing as a.

foundation and exposed .to the atmosphere, andthe other parts of the cylinders being located within `the casing, so that the heat radiated ltherefrom shall be absorbed by the cool supply-air on its route to the furnace.

Second. In a peculiar construction and arrangement, substantially such as herein 1s described andis illustrated in the drawings, of-v .the hot-air cylinder, thepacked part of its piston, and a piston-trunk, which, with the necessary packing, valves, and other 'adj uncts, form a' pumpA by which cold air is compressed and supplied to the furnace to be expanded by heat. The pump, being annular, is exposed,insid e aswell as outside, tothe cooling inlluence of the atmosphere, and, when Icoinpressing the-supply-air, being operated by the direct'pressu re of the expanded heated -air on the enginefpiston. Thehvstrain necessary to ccinpres.s the supply-air', isY applied directly.A

and is not transmitted through the rotative parts of the mechanism. By this annular arrangement of the pump l am enabled to re duce the height, which would btherwise be" needed by my engine, by connecting thepit.-l `man direct to the engine-piston. The pitman thus vibrates within the trunk, and good facilities are had for keeping cool the joint of the .pitman with the piston and for lubricating it. I I

Third Inaconstnuction of thecylinder,sub

stantially such as is herein described and is -illustrated in the drawings, and more particu. larly detailedon Sheet No. 3, Figure 6, which` consists in agroove or chamber formed around the interior ofv the cylinder at 4that part thereof where the lower edgeV of the closely-f fitting portion of-the pistoncomes at the low" air, by means hereinafter described, for the purpose of keeping the piston-packing cool and that part of the interior surface of the cylinder against which the piston slides and to keep solid products of combustion from 'rising tothe upper-part of the cylinder with each incoming suppl y from the furnace. This chamber or groove also serves to receive the lubricating-fluid whichescapes past the packed portion of thepiston, and as much more as, may be introduced therein by means of oil-pumps, rbc. Into the fluidcontained .in this groove the lower edge oi". the piston may be made to dip, and so lubricatcthe in ner surface of the cylinder at each stroke of the piston. The groove or chamber may Abe made to receive an isolated circular trough to receive the oil, as shown in Fig. '6, which' ing such solid matter from the furnace as may est point in its downward stroke. This chamber receives a supplyof pure 'cool compressed find ent-rance into the cylinder along with the gaseous products of combustion and preventing the saine from abrading the finished surfaces of the piston and cylinder.

Fifth. In the employment of au auxiliary valve operating to admit from the reservoir in which the air is maintained under pressure comparatively cool and compressed air into the circular groove around the cylinder and into the clearance-spaces within and conneeted with the cylinder for the double purpose of balancing the pressure upon the main inlet-valve into the cylinder and to maintain the finished surfaces of the piston and cylinder, where one moves upon the other, at a temperature which will not prevent lubrication.

Sixth. 1n regulating the speed of hot-air engines by controlling the flow of the' heated compressed air and gaseous products of combustion, or the supply thereof to the enginecylinders' by means of a valve controlled by a regulator dependent upon the speed of the engine, instead of permitting such a regulaq tor to opcratea valve to open communication through which the generated pressure is permitted to escape and be lost without acting to impel the pistons.

In the drawings, Fig. 1, Sheet No. 1, illustrates in half-side elevation and in half-sectional elevation a hot-air or caloric engine embodying my invention, the section being taken in the lines 1/ y, Fig. 2, and .a e', Fig.

Fig. 2, Sheet-No. 2, is an end elevation of the same, a part, however, being shown in section, taken in the lines y y', Fig. 1, and 00',Fig. 3, for the purpose of showing the fuel-feed box. Fig. 3, Sheet No. 3, illustrates the same in half-plan and in half-horizontal section, taken in the lines z .2", Fig. 1, and .22 z2, Fig. 2.

' Fig. 1, Sheet No. 4, supplement, shows a horizontal section taken through the furnace j ust beneath the crown-plate and cutting the supply-pipe 1l, so as to show fully the throttlevalvep. Fig. 5 is a sectional elevation taken in the line 'U2 y?, Fig. 3, of so much of the cylinder' and the parts connected therewith as to illustrate how the exhaust escapes into the radiator or heater. Fig. 'U shows in section the groove or chamber in the cylinder,"

Centrally located in E is the f .irnace, linedl with tire-brick J, Figs. 1, 3, and 1, and provided with gra'tes c, Figs. 1 and 4, and an ashpit, which has an air-tight door I, Figs. 1, 2,

' Fig. 2, and a Valve-rod which passes through a packing in the fuel-box.

A piston-head g, with its rod h, (see Fig.

A2,) serves to thrust the fuel forward in the fuel-box, so that it may all fall into the furnace through the aperture closed by valve e, Fig. By this arrangement and its proper manipulation, which will be seen by inspeetion lof the drawings, it is obvious that the fire may be replenished with fresh fuel while there is the requisite pressure within the furnace and casing needed to operate the engine without reducing the pressure or impeding the operation of the engine.

The furnace is provided with openings a', Figzhbelow the grates and with others a2, Figs. 1 and 4, above the top of the fuel, through which air under pressure is supplied by means hereinafter to be described, L'hich air is introduced into the 'space contained between t-he outside casing l), Figs. 1, 2, 3, and 4, of the furnace and the casing t, Figs. 1, 2, and 3, which next surrounds it. The Working-eylindersof which there are two, are located within and upon the casing and upon opposite sides of the furnace. These cylinders are single-actingthat is, the piston of .each is forced upward by admitting the com-- pressed heated air and gases from within the furnace beneath the piston, and both pistons being connected to the main shaft. R, Figs. 1

land 3, by cranks at right angles with each other. The downward movement of each pist0n is produced by the upward movement of g the other acting through the shaftin connection with the balance-wheel. Each cylinder may be described as in two sections, the upper section A, Figs. 1 and 2, standing above and outside of the casing or bed-plate and being finished inside sov that a closely-fitting packed piston D, Fig. 1, may move freely therein, after the manner of steam-engine pistons within their cylinders. The lower section B, Figs. 3 and -6, is within the bedplate or casing. This section need not be bored out or nished, as the extension part F, Fig. 1, of the piston, which plays in the lower section of the cylinder,is not intended.

to come into Contact with it, and when at the lowest point of its downward stroke leaves an does not need further explanatiouthan is af forded by the drawings, Fig. 1. Tile pistonfollower c', Fig. 1, is the flange of the-pipe or trunk C,-Figs. 1, 2, and 3, In this trunk the connecting-rod or pitman P, Figs. 1, 2, and 3, plays, and is connected to the pisto-headby a Joint, as shown in Fig. 1, which is kept cool by free exposure tothe atmosphere and by lubrication, for which good facilities -are afforded. The trunk passes through the upper head t', Figs. 1, 2, and 3, of the cylindeigwhere it is packed-with leather and guided by the gland 1', Figs. -1, 2, and 3. The upper cylin'- der-head is furnished with a valve o, Fig. 1, which when forced open by the compression of the air in the annular spacebetween the trunk and the upper section of the cylinder permits the said compressed air to pass into the easing through the valve-box K and pipe L, Figs. 1 and 2. It will be obvious that thepiston iu its ascent will compress t-he air in the said annular space till its density'is equal to .that of the gaseous contents'of the casing,

when further movement of the pist-on upward` opens the outlet-valve and displaces the L,compressed air. The upper cylinder-head is also `furnished 7with valves vn, Figs. 2 and 3, the purpose of which is to open to admit air within the annular pump when .the piston descends and to close and remain closed atother times. Supposing the engine to be in motiomthe air which is takemin by tle pumps and thrown out by 'each stroke of each piston passes, as is indicated by the arrows in Fig. 1, along the division-platej, Figs. 1- and 2, which extends horizontally entirely across the space contained within the casing to an opening in the center of said plate; then between said plate and a second horizontal plate k, Figs. 1 and 2; from thence downward between the outer vertical boundary of the casing and an in- -ternal partition m, Figs. 1, 2, and 3, parallel with said outer boundary, and extending enf ltirely around withinthe casing; then vertic ally upward between partitions 'm and Z, Figs. 1, 2, and 3, into a space contained be tween l and t, Figs. 1, 2, and 3, whence the air passes into the furnace through apertures a', Fig. 1,. and a2, Figs. l and 4, the position of the dampers 9, Figs. 1 and 4, determining what portion of the air shall pass into the furnace through the fuel and what above it.

Havingdescribcd how 'air is compressed and forced into the furnace, I will now show how, 'when expanded by heat, it passes into the cylinders and is exhausted therefrom, thereby producing reciprocatious of the pistons and .developing the power generated by heating. the air. i

In the 'top of the furnace and passing through it to the inlet-valve boxes 0, Figs. 1 and 3, is a suitably-shaped pipe h', Figs. 2

. and 4, with an aperture therein opening into the furnace, which c n be opened and closed by a throttle-val ve p, Figs. 1 and 4'.v Thisvalve is operated by a governor or regulator Q, Figs. 1 and 3, operating on a lever fixed to the valve-stem by means of the connection q, '-Figs. 1- and 2. The heated air` and gaseous products of combustion, mingled, pass into `this pipe in amou-nt regulated by the position af the'throttlelvalve, and when the inlet-valve et either-cylinder is opened they pass intel the inlet-valve has been closed the exhaustvalve opens and permits the contents of the cylinder to escape and to be forced out by the' descent of the pistou in to the open air throughthe passage N, Fig. 5, and the 'radiator or heater G, Figs. 1,. 3, and ,.lecated in the space through which air passes' on its` way, to beheated in the furnace. The valves shown in the drawings are of the puppet variety and are operated at proper times by 1fter-tappets on the valve-rods and on rocker-shafts worked from eccentrics S, Figs. 1, 2, and. 3, on the main shaft. There is nothing pecul-iarabout the valves or valve-gear, and any other which is adapted to the ingress' and egress of the heated air and known to engineers inthc practice of their profession may be used for those sh0wn,'though Iprefer to use valves of the puppet variety. I f

The form o f the heater is immaterial.. 'That shown presents a large surface for radiation, and the diaphragm-plates a, Figs. land 5, within the heaterv compel a tortuous passage of the exhaust. It will be seen that the dis position'of division plates and partitions before mentioned is such as to'causethe gradual heating of the cold compressed air on its way from the pump to the furnace by the-absorption of the heat from the radiation from the lower partof the cylinder, the conveyingpipes, heater, and boundaries of thefu-rnace, so that the radiated, heat is nearly all utilized, and the desideratum is attained of having a comparatively cool surface tothe outer or exposed surface and parts of the machine. A dead-air space is formed inthe casing between its base-plate and the compressed and heated air to prevent radiation of heat from Athe lower surface of the casing.

-At the juncture of the upper and lowersections of the cylinder and at the lower edge of the close-litting part of the piston a groove or chamber c', Figs. 1 and 6, vis formed entirelyaround the cylinder. At the upper inner edge of the lower section of the cylinder is an inward projecting tlange s, Figs. 1 and 6, which forms the bottom of the groove and extends-inward from the general surface of the lower part of the cylinder, so as almost to touch the lower or extended part of the piston. The groove or vchannbcr round the cylin`- der communicates with the compressed air in the upper -part ofthc casing` where it is comparatively cool and pure. This communication is made by the means of pi-pe w', Fig. 1, which terminates in the valve-box be', Fig. 12, in which the puppet-valve u, Fig, 1, operates by 'any suitable mechanism, thatshow-n being a wiper or arm Ona rockershatt acting en the valve-'stento open the val ve againstthepress the valve may be located.

ure of a spring, the reacting of which assists to close it. It will be seen that when the valve u, Fig. l, is open air will fiow into the cylinder from the casing at such spot as lf this valve is opened, as it should be, after the exhaustvalve closes and before the main inlet opens, all the clearances or unoccupied space in the cylinder and valve-passages will be filled with pure air, but little heated and of density equal to that within theA casing' and furnace.

The object of introducing air through pipe tu, Fig. l, from and at about the place and at the time mentioned is threefold. First, by rendering the pressure alike on both sides of the inlet-valve it is balanced and operated in equilibrium, by which the power necessary to -Work it is reduced to the minimum; second,

by having the spaces in the cylinder filled with. pure air that which rushes afterward into the cylinder from the furnace will not be` apt to carry the solid products ofcombustion into the joints between the finished portions of the piston and cylinder; third, by the introduction o f cool compressed air, as de scribed, the temperature of the finished parts of the piston and cylinder which come into contact are kept sufficiently cool to admit of efficient lubrication. l l

The inwardly-projecting flange s, Figs. l and 6, serves to doliect or to render difficult the passage of any particle ot' solid matter coming into thecylinderwith the heated air and gaseous products of combustion, and the lower 'edge of the packed part of the piston is made of the shape shown in Fig. 1 to aid in kee in@ solid matter from enter-infr betweenv P e s the finished surfaces of the piston and cylinder and from abrading them.

The chamber fu, Figs. 1 and G, serves to catch the o-il which passes by the piston, or lubricating matter may be injected therein by an oilpump. A pipe provided with a stop-cock will afford means for drawing 0E accumulations of lubricating matter, together with such solid matter as may be deposited there, while the lower edge of the pistonpacking by dipping into the oil at each down ward stroke will aid in keeping the workingsurface's well lubricated.

An improvement upon the simple chamber consists in placing thereina circular oiltrough M, ee Fig. 6,) which is sustained at a little distance from the metal of the cylinder by ears placed at intervals around the trough. The current cf cool air from the auxiliary valve will pass through the space around the trough, cutting 0E communication of the heat conducted by the metal of the cylinder and preventing evaporation and burning of the lubricating material.

In starting a fire on the gratos the maininf let, exhaust, and throttle valves should be openedas well as the ash-pit door, to establish a draft through the engine by way of the' cylinder and radiator. If sufiieientdraft canlshould be openedand a direct upward draft thereby established, which may be conducted by a temporary funnel. Then the fuel is well ignited, all the doors and valves through which air can pass to or from the casing should be closed and secured and air should be supplied by a pump to support combustion and to force and compress air Within the casing, where it will be expanded fronfthe heat generated by the burning fuel. The means by which air may be forced into, the furnace while establishing a sufcient pressure therein to start the engine may be a forcepump or fan or other equivalent device 0perated by hand or by any otherconvenient and suitable power; .or the main shaft of thel engine itself may be rotated by suitable means, when the pumps forming part of the engine will supply the air needed in the furnace. lVhen sufficient pressure has been generated to rotate the engine, the extraneous force may be discontinued, as the expansion of the air supplied by the pumps of the engine will continue to increase the pressure within the casing till the engine has some work applied to it to absorb the power generated. v f

A safety-valve may be applied to the casing and so regulated as to prevent the increase of pressure to a point which would endanger the integrity of the machine.

It should be observed that the valve-chest covers, through which pass the valve#stems, are provided` with pipes T, Fig. 5, which extend througnn the casing for f Bae purpose of bringing the packings of the valve-stems to a position where they are not materially at`- fected by the heat from the furnace.

Having described my invention, what I claim as new, and desire to have secured to me by Letters Patent, is`

1. The combined arrangement, in a caloricengine, operating substantially as herein shown and described, of the cylinders, pistons, reservoir, and furnace, the cylinders and .their access ,nies acting together to rotate one shaft, and the cylinders being located partly within and partly without the reservoir, which contains a supply of compressed and heated air, and a furnace which heats the s'aid supply, which, with the gaseous products of combustion, passes through the engine.

2. The combination of the finished or upper part of the cylinder with-its head, piston, Y and trunk therewith connected, all operating together, su bstantially as described, and with inlet and outlet valves, and suitable packing round the said trunk to form an annular airpump.

3. 'lhe chamber or groove around the cylinder arranged and operating, substantial! y as specified, at or near where the lower part of the pist-on. comes at the termination -ot` its downward movement. 1

, for the specified purpo'se.

4; The isolated oil-trough within the chamwhich it is constantly maintained compressed, bei' 0 1 groove around and within the cylinder, ab the pince anti times and by suitable valve- Y gearing,- substantially as and for the purposes 5. The in wadly projecing'fange arspecified. ranged and operating substtalLy-as shown PHILANDER SHAW.

and described. Witnesses:

6. Admit-ting into the yliner compara J. B. CROSBY,` tively pure and cool air from a, reservoir, in GALEN COFFIN- 

